// This is an open source non-commercial project. Dear PVS-Studio, please check
// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com


#include "nvim/tui/input.h"
#include "nvim/vim.h"
#include "nvim/api/vim.h"
#include "nvim/api/private/helpers.h"
#include "nvim/ascii.h"
#include "nvim/charset.h"
#include "nvim/main.h"
#include "nvim/aucmd.h"
#include "nvim/ex_docmd.h"
#include "nvim/option.h"
#include "nvim/os/os.h"
#include "nvim/os/input.h"
#include "nvim/event/rstream.h"

#define PASTETOGGLE_KEY "<Paste>"
#define KEY_BUFFER_SIZE 0xfff

#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "tui/input.c.generated.h"
#endif

void term_input_init(TermInput *input, Loop *loop)
{
  input->loop = loop;
  input->paste_enabled = false;
  input->in_fd = 0;
  input->key_buffer = rbuffer_new(KEY_BUFFER_SIZE);
  uv_mutex_init(&input->key_buffer_mutex);
  uv_cond_init(&input->key_buffer_cond);

  const char *term = os_getenv("TERM");
  if (!term) {
    term = "";  // termkey_new_abstract assumes non-null (#2745)
  }

#if TERMKEY_VERSION_MAJOR > 0 || TERMKEY_VERSION_MINOR > 18
  input->tk = termkey_new_abstract(term,
                                   TERMKEY_FLAG_UTF8 | TERMKEY_FLAG_NOSTART);
  termkey_hook_terminfo_getstr(input->tk, input->tk_ti_hook_fn, NULL);
  termkey_start(input->tk);
#else
  input->tk = termkey_new_abstract(term, TERMKEY_FLAG_UTF8);
#endif

  int curflags = termkey_get_canonflags(input->tk);
  termkey_set_canonflags(input->tk, curflags | TERMKEY_CANON_DELBS);
  // setup input handle
#ifdef WIN32
  uv_tty_init(&loop->uv, &input->tty_in, 0, 1);
  uv_tty_set_mode(&input->tty_in, UV_TTY_MODE_RAW);
  rstream_init_stream(&input->read_stream,
                      (uv_stream_t *)&input->tty_in,
                      0xfff);
#else
  rstream_init_fd(loop, &input->read_stream, input->in_fd, 0xfff);
#endif
  // initialize a timer handle for handling ESC with libtermkey
  time_watcher_init(loop, &input->timer_handle, input);
}

void term_input_destroy(TermInput *input)
{
  rbuffer_free(input->key_buffer);
  uv_mutex_destroy(&input->key_buffer_mutex);
  uv_cond_destroy(&input->key_buffer_cond);
  time_watcher_close(&input->timer_handle, NULL);
  stream_close(&input->read_stream, NULL, NULL);
  termkey_destroy(input->tk);
}

void term_input_start(TermInput *input)
{
  rstream_start(&input->read_stream, read_cb, input);
}

void term_input_stop(TermInput *input)
{
  rstream_stop(&input->read_stream);
  time_watcher_stop(&input->timer_handle);
}

static void input_done_event(void **argv)
{
  input_done();
}

static void wait_input_enqueue(void **argv)
{
  TermInput *input = argv[0];
  RBUFFER_UNTIL_EMPTY(input->key_buffer, buf, len) {
    size_t consumed = input_enqueue((String){.data = buf, .size = len});
    if (consumed) {
      rbuffer_consumed(input->key_buffer, consumed);
    }
    rbuffer_reset(input->key_buffer);
    if (consumed < len) {
      break;
    }
  }
  uv_mutex_lock(&input->key_buffer_mutex);
  input->waiting = false;
  uv_cond_signal(&input->key_buffer_cond);
  uv_mutex_unlock(&input->key_buffer_mutex);
}

static void flush_input(TermInput *input, bool wait_until_empty)
{
  size_t drain_boundary = wait_until_empty ? 0 : 0xff;
  do {
    uv_mutex_lock(&input->key_buffer_mutex);
    loop_schedule(&main_loop, event_create(wait_input_enqueue, 1, input));
    input->waiting = true;
    while (input->waiting) {
      uv_cond_wait(&input->key_buffer_cond, &input->key_buffer_mutex);
    }
    uv_mutex_unlock(&input->key_buffer_mutex);
  } while (rbuffer_size(input->key_buffer) > drain_boundary);
}

static void enqueue_input(TermInput *input, char *buf, size_t size)
{
  if (rbuffer_size(input->key_buffer) >
      rbuffer_capacity(input->key_buffer) - 0xff) {
    // don't ever let the buffer get too full or we risk putting incomplete keys
    // into it
    flush_input(input, false);
  }
  rbuffer_write(input->key_buffer, buf, size);
}

static void forward_simple_utf8(TermInput *input, TermKeyKey *key)
{
  size_t len = 0;
  char buf[64];
  char *ptr = key->utf8;

  while (*ptr) {
    if (*ptr == '<') {
      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "<lt>");
    } else {
      buf[len++] = *ptr;
    }
    ptr++;
  }

  enqueue_input(input, buf, len);
}

static void forward_modified_utf8(TermInput *input, TermKeyKey *key)
{
  size_t len;
  char buf[64];

  if (key->type == TERMKEY_TYPE_KEYSYM
      && key->code.sym == TERMKEY_SYM_ESCAPE) {
    len = (size_t)snprintf(buf, sizeof(buf), "<Esc>");
  } else if (key->type == TERMKEY_TYPE_KEYSYM
      && key->code.sym == TERMKEY_SYM_SUSPEND) {
    len = (size_t)snprintf(buf, sizeof(buf), "<C-Z>");
  } else {
    len = termkey_strfkey(input->tk, buf, sizeof(buf), key, TERMKEY_FORMAT_VIM);
  }

  enqueue_input(input, buf, len);
}

static void forward_mouse_event(TermInput *input, TermKeyKey *key)
{
  char buf[64];
  size_t len = 0;
  int button, row, col;
  static int last_pressed_button = 0;
  TermKeyMouseEvent ev;
  termkey_interpret_mouse(input->tk, key, &ev, &button, &row, &col);

  if ((ev == TERMKEY_MOUSE_RELEASE || ev == TERMKEY_MOUSE_DRAG)
      && button == 0) {
    // Some terminals (like urxvt) don't report which button was released.
    // libtermkey reports button 0 in this case.
    // For drag and release, we can reasonably infer the button to be the last
    // pressed one.
    button = last_pressed_button;
  }

  if (button == 0 || (ev != TERMKEY_MOUSE_PRESS && ev != TERMKEY_MOUSE_DRAG
                      && ev != TERMKEY_MOUSE_RELEASE)) {
    return;
  }

  row--; col--;  // Termkey uses 1-based coordinates
  buf[len++] = '<';

  if (key->modifiers & TERMKEY_KEYMOD_SHIFT) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "S-");
  }

  if (key->modifiers & TERMKEY_KEYMOD_CTRL) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "C-");
  }

  if (key->modifiers & TERMKEY_KEYMOD_ALT) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "A-");
  }

  if (button == 1) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Left");
  } else if (button == 2) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Middle");
  } else if (button == 3) {
    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Right");
  }

  switch (ev) {
    case TERMKEY_MOUSE_PRESS:
      if (button == 4) {
        len += (size_t)snprintf(buf + len, sizeof(buf) - len, "ScrollWheelUp");
      } else if (button == 5) {
        len += (size_t)snprintf(buf + len, sizeof(buf) - len,
                                "ScrollWheelDown");
      } else {
        len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Mouse");
        last_pressed_button = button;
      }
      break;
    case TERMKEY_MOUSE_DRAG:
      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Drag");
      break;
    case TERMKEY_MOUSE_RELEASE:
      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Release");
      break;
    case TERMKEY_MOUSE_UNKNOWN:
      assert(false);
  }

  len += (size_t)snprintf(buf + len, sizeof(buf) - len, "><%d,%d>", col, row);
  enqueue_input(input, buf, len);
}

static TermKeyResult tk_getkey(TermKey *tk, TermKeyKey *key, bool force)
{
  return force ? termkey_getkey_force(tk, key) : termkey_getkey(tk, key);
}

static void timer_cb(TimeWatcher *watcher, void *data);

static int get_key_code_timeout(void)
{
  Integer ms = -1;
  // Check 'ttimeout' to determine if we should send ESC after 'ttimeoutlen'.
  Error err = ERROR_INIT;
  if (nvim_get_option(cstr_as_string("ttimeout"), &err).data.boolean) {
    Object rv = nvim_get_option(cstr_as_string("ttimeoutlen"), &err);
    if (!ERROR_SET(&err)) {
      ms = rv.data.integer;
    }
  }
  api_clear_error(&err);
  return (int)ms;
}

static void tk_getkeys(TermInput *input, bool force)
{
  TermKeyKey key;
  TermKeyResult result;

  while ((result = tk_getkey(input->tk, &key, force)) == TERMKEY_RES_KEY) {
    if (key.type == TERMKEY_TYPE_UNICODE && !key.modifiers) {
      forward_simple_utf8(input, &key);
    } else if (key.type == TERMKEY_TYPE_UNICODE
               || key.type == TERMKEY_TYPE_FUNCTION
               || key.type == TERMKEY_TYPE_KEYSYM) {
      forward_modified_utf8(input, &key);
    } else if (key.type == TERMKEY_TYPE_MOUSE) {
      forward_mouse_event(input, &key);
    }
  }

  if (result != TERMKEY_RES_AGAIN || input->paste_enabled) {
    return;
  }

  int ms  = get_key_code_timeout();

  if (ms > 0) {
    // Stop the current timer if already running
    time_watcher_stop(&input->timer_handle);
    time_watcher_start(&input->timer_handle, timer_cb, (uint32_t)ms, 0);
  } else {
    tk_getkeys(input, true);
  }
}

static void timer_cb(TimeWatcher *watcher, void *data)
{
  tk_getkeys(data, true);
  flush_input(data, true);
}

/// Handle focus events.
///
/// If the upcoming sequence of bytes in the input stream matches the termcode
/// for "focus gained" or "focus lost", consume that sequence and schedule an
/// event on the main loop.
///
/// @param input the input stream
/// @return true iff handle_focus_event consumed some input
static bool handle_focus_event(TermInput *input)
{
  if (rbuffer_size(input->read_stream.buffer) > 2
      && (!rbuffer_cmp(input->read_stream.buffer, "\x1b[I", 3)
          || !rbuffer_cmp(input->read_stream.buffer, "\x1b[O", 3))) {
    // Advance past the sequence
    bool focus_gained = *rbuffer_get(input->read_stream.buffer, 2) == 'I';
    rbuffer_consumed(input->read_stream.buffer, 3);
    aucmd_schedule_focusgained(focus_gained);
    return true;
  }
  return false;
}

static bool handle_bracketed_paste(TermInput *input)
{
  if (rbuffer_size(input->read_stream.buffer) > 5
      && (!rbuffer_cmp(input->read_stream.buffer, "\x1b[200~", 6)
          || !rbuffer_cmp(input->read_stream.buffer, "\x1b[201~", 6))) {
    bool enable = *rbuffer_get(input->read_stream.buffer, 4) == '0';
    // Advance past the sequence
    rbuffer_consumed(input->read_stream.buffer, 6);
    if (input->paste_enabled == enable) {
      return true;
    }
    enqueue_input(input, PASTETOGGLE_KEY, sizeof(PASTETOGGLE_KEY) - 1);
    input->paste_enabled = enable;
    return true;
  }
  return false;
}

static bool handle_forced_escape(TermInput *input)
{
  if (rbuffer_size(input->read_stream.buffer) > 1
      && !rbuffer_cmp(input->read_stream.buffer, "\x1b\x00", 2)) {
    // skip the ESC and NUL and push one <esc> to the input buffer
    size_t rcnt;
    termkey_push_bytes(input->tk, rbuffer_read_ptr(input->read_stream.buffer,
          &rcnt), 1);
    rbuffer_consumed(input->read_stream.buffer, 2);
    tk_getkeys(input, true);
    return true;
  }
  return false;
}

static void set_bg_deferred(void **argv)
{
  char *bgvalue = argv[0];
  if (!option_was_set("bg") && !strequal((char *)p_bg, bgvalue)) {
    // Value differs, apply it.
    if (starting) {
      // Wait until after startup, so OptionSet is triggered.
      do_cmdline_cmd((bgvalue[0] == 'l')
                     ? "autocmd VimEnter * ++once ++nested set bg=light"
                     : "autocmd VimEnter * ++once ++nested set bg=dark");
    } else {
      set_option_value("bg", 0L, bgvalue, 0);
      reset_option_was_set("bg");
    }
  }
}

// During startup, tui.c requests the background color (see `ext.get_bg`).
//
// Here in input.c, we watch for the terminal response `\e]11;COLOR\a`.  If
// COLOR matches `rgb:RRRR/GGGG/BBBB` where R, G, and B are hex digits, then
// compute the luminance[1] of the RGB color and classify it as light/dark
// accordingly. Note that the color components may have anywhere from one to
// four hex digits, and require scaling accordingly as values out of 4, 8, 12,
// or 16 bits.
//
// [1] https://en.wikipedia.org/wiki/Luma_%28video%29
static bool handle_background_color(TermInput *input)
{
  size_t count = 0;
  size_t component = 0;
  uint16_t rgb[] = { 0, 0, 0 };
  uint16_t rgb_max[] = { 0, 0, 0 };
  bool eat_backslash = false;
  bool done = false;
  bool bad = false;
  if (rbuffer_size(input->read_stream.buffer) >= 9
      && !rbuffer_cmp(input->read_stream.buffer, "\x1b]11;rgb:", 9)) {
    rbuffer_consumed(input->read_stream.buffer, 9);
    RBUFFER_EACH(input->read_stream.buffer, c, i) {
      count = i + 1;
      if (eat_backslash) {
        done = true;
        break;
      } else if (c == '\x07') {
        done = true;
        break;
      } else if (c == '\x1b') {
        eat_backslash = true;
      } else if (bad) {
        // ignore
      } else if (c == '/') {
        if (component < 3) {
          component++;
        }
      } else if (ascii_isxdigit(c)) {
        if (component < 3 && rgb_max[component] != 0xffff) {
          rgb_max[component] = (uint16_t)((rgb_max[component] << 4) | 0xf);
          rgb[component] = (uint16_t)((rgb[component] << 4) | hex2nr(c));
        }
      } else {
        bad = true;
      }
    }
    rbuffer_consumed(input->read_stream.buffer, count);
    if (done && !bad && rgb_max[0] && rgb_max[1] && rgb_max[2]) {
      double r = (double)rgb[0] / (double)rgb_max[0];
      double g = (double)rgb[1] / (double)rgb_max[1];
      double b = (double)rgb[2] / (double)rgb_max[2];
      double luminance = (0.299 * r) + (0.587 * g) + (0.114 * b);  // CCIR 601
      char *bgvalue = luminance < 0.5 ? "dark" : "light";
      DLOG("bg response: %s", bgvalue);
      loop_schedule_deferred(&main_loop,
                             event_create(set_bg_deferred, 1, bgvalue));
    } else {
      DLOG("failed to parse bg response");
    }
    return true;
  }
  return false;
}

static void read_cb(Stream *stream, RBuffer *buf, size_t count_, void *data,
                    bool eof)
{
  TermInput *input = data;

  if (eof) {
    if (input->in_fd == 0 && !os_isatty(0) && os_isatty(2)) {
      // Started reading from stdin which is not a pty but failed. Switch to
      // stderr since it is a pty.
      //
      // This is how we support commands like:
      //
      // echo q | nvim -es
      //
      // and
      //
      // ls *.md | xargs nvim
      input->in_fd = 2;
      stream_close(&input->read_stream, NULL, NULL);
      multiqueue_put(input->loop->fast_events, restart_reading, 1, input);
    } else {
      loop_schedule(&main_loop, event_create(input_done_event, 0));
    }
    return;
  }

  do {
    if (handle_focus_event(input)
        || handle_bracketed_paste(input)
        || handle_forced_escape(input)
        || handle_background_color(input)) {
      continue;
    }

    // Find the next 'esc' and push everything up to it(excluding). This is done
    // so the `handle_bracketed_paste`/`handle_forced_escape` calls above work
    // as expected.
    size_t count = 0;
    RBUFFER_EACH(input->read_stream.buffer, c, i) {
      count = i + 1;
      if (c == '\x1b' && count > 1) {
        count--;
        break;
      }
    }

    RBUFFER_UNTIL_EMPTY(input->read_stream.buffer, ptr, len) {
      size_t consumed = termkey_push_bytes(input->tk, ptr, MIN(count, len));
      // termkey_push_bytes can return (size_t)-1, so it is possible that
      // `consumed > input->read_stream.buffer->size`, but since tk_getkeys is
      // called soon, it shouldn't happen
      assert(consumed <= input->read_stream.buffer->size);
      rbuffer_consumed(input->read_stream.buffer, consumed);
      // Need to process the keys now since there's no guarantee "count" will
      // fit into libtermkey's input buffer.
      tk_getkeys(input, false);
      if (!(count -= consumed)) {
        break;
      }
    }
  } while (rbuffer_size(input->read_stream.buffer));
  flush_input(input, true);
  // Make sure the next input escape sequence fits into the ring buffer
  // without wrap around, otherwise it could be misinterpreted.
  rbuffer_reset(input->read_stream.buffer);
}

static void restart_reading(void **argv)
{
  TermInput *input = argv[0];
  rstream_init_fd(input->loop, &input->read_stream, input->in_fd, 0xfff);
  rstream_start(&input->read_stream, read_cb, input);
}
